1. Field of the Invention
The present invention relates to display panel driving methods for driving display panels such as plasma display panels (hereafter, “PDP”) and electroluminescence (hereafter, “EL”) panels.
2. Description of the Related Art
Display devices that use self-light emitting flat display panels such as PDPs and EL panels are currently being commercialized as so-called wall-mounted TVs. As a display device using a PDP as a display panel, for example there is the art disclosed in Japanese Patent Kokai No. 2000-155557 (Patent Document 1). An overall configuration of the drive circuit in the PDP display device disclosed in Patent Document 1 is shown in the block diagram of FIG. 1.
In FIG. 1, a display panel PDP 10 has row electrodes X1 to Xn and row electrodes Y1 to Yn, which are formed such that each pair of a row electrode X and a row electrode Y constitutes a row electrode pair corresponding to a row (first row to n-th row) of one screen. Furthermore, in the PDP 10, column electrodes Z1 to Zm are formed perpendicular to the row electrodes, sandwiching a dielectric layer and a discharge space layer, which are not shown in the drawing, and correspond to columns (first column to m-th column) of one screen. It should be noted that a single discharge cell C(i, j) is formed at the intersecting portion of each single pair of row electrodes (Xi, Yi) and single column electrode Zj.
First, a row electrode drive circuit 30 produces a positive reset pulse RPy like that shown in FIG. 2, which is simultaneously applied to each of the row electrodes Y1 to Yn. At the same time, a row electrode drive circuit 40 produces a negative reset pulse RPx, which is simultaneously applied to all the row electrodes X1 to Xn.
By simultaneously applying the reset pulses RPx and RPy, a discharge is induced in all the discharge cells of the PDP 10, generating charged particles. Subsequent to the completion of this discharge, a predetermined wall charge is formed uniformly in the dielectric layer of all the discharge cells. This processing step is referred to as a reset step.
After the completion of the reset step, a column electrode drive circuit 20 produces pixel data pulses DP1 to DPn corresponding to pixel data that corresponds to the first to n-th rows of the screen. The pixel data pulses are then applied successively to the column electrodes Z1 to Zm as shown in FIG. 2. Meanwhile, the row electrode drive circuit 30 produces negative scan pulses SP corresponding to the timing of the application of the pixel data pulses DP1 to DPn. Then, as shown in FIG. 2, the negative scan pulses are applied successively to the row electrodes Y1 to Yn.
Within the discharge cells of the row electrodes to which the scan pulses SP are applied, a discharge is produced in the discharge cells to which a further positive pixel data pulse DP is simultaneously applied, and most of the wall charge therein is lost. On the other hand, as no discharge is produced in the discharge cells to which a scan pulse SP has been applied but a positive pixel data pulse DP has not been applied, the above-mentioned wall charge remains as it is. At this time, the discharge cells in which the wall charge remains as it is become light-emitting discharge cells, and the discharge cells in which the wall charge is extinguished become non-light-emitting discharge cells. This processing step is referred to as an addressing step.
When the addressing step is completed, the row electrode drive circuit 30 continuously applies positive sustain pulses IPY to the row electrodes Y1 to Yn as shown in FIG. 2. In conjunction with this, the row electrode drive circuit 40 continuously applies positive sustain pulses IPX to the row electrodes X1 to Xn with a timing that is offset against the timing of the sustain pulses IPY. During the period in which the sustain pulses IPX and IPY are alternately applied, discharge light emissions are repeated by the light-emitting discharge cells in which the above-mentioned wall charge remains as it is, thus maintaining a light-emitting state. This processing step is referred to as a sustain step.
A drive control circuit 50, as shown in FIG. 1, produces various switching signals based on the timing of the supplied video signal in order for the various drive pulses shown in FIG. 2 to be produced. These switching signals are then supplied to the above-mentioned column electrode drive circuit 20, and the row electrode drive circuits 30 and 40. That is, the column electrode drive circuit 20 and the row electrode drive circuits 30 and 40 produce the drive pulses shown in FIG. 2 in response to the switching signals supplied from the drive control circuit 50.
Furthermore, pulse generating circuits, which generate the various drive pulses such as the reset pulse RPY and the sustain pulses IPX and IPY, are provided for each row and column electrode inside the above-mentioned electrode drive circuits. It should be noted that all of these pulse generating circuits use the charging and discharging of capacitors in LC resonance circuits made of an inductor L and a capacitor C to generate the various drive pulses.
In other words, the resonance circuits are formed combining inductors, which are inductive elements, and capacitors for power collection exploiting the fact that the discharge cells C(i, j) of the PDP 10 are capacitive loads. A desired driving pulse is then generated by exciting the resonance circuits with a predetermined timing by opening and closing switching elements such as FETs in response to switching signals supplied from the drive control circuit 50.
In this way, the prior art described above aim to improve power dissipation when driving a display panel by using resonance circuits for the circuits that drive the discharge cells, which constitute capacitive loads. However, generally a comparatively high voltage of around several tens to one hundred and several tens of volts is used when exciting discharge cells with resonance circuits. For this reason, the power dissipation is still large when driving a display panel and there is a need for improved reductions in reactive power.
The present invention has been made to solve such a problem as described above. Examples of the objects to be attained by the present invention include, for example, providing a display panel driving method that can reduce power consumption when exciting discharge cells.